Combination mast and light raising and lowering apparatus

ABSTRACT

A light carrying frame preferably in the form of a ring-like structure in spaced encircling relationship to a mast is provided with supporting cables extending upwardly from the frame and around pulleys at the top of the mast. The cables pass down through the mast to a windlass apparatus at the bottom thereof for raising and lowering the portion of the cables extending upwardly from the frame. Releasable supporting means are provided adjacent the upper portion of the mast for supporting the weight of the light carrying unit when it is raised to a lighting position. Signalling means are provided for signalling to the operator below when the light carrying unit is in its lighting position at the upper portion of the mast.

United States Patent [1 1 Kiehn 51 Apr. 2,1974

COMBINATION MAST AND LIGHT RAISING AND LOWERING APPARATUS [76] Inventor: Mogens Kiehn, 1740 Waukegan Rd., Glenview, 111. 60025 [22] Filed: Sept. 14, 1972 21 Appl. No.: 289,090

[56] References Cited UNITED STATES PATENTS 151,083 5/1874 Buck 248/330 FOREIGN PATENTS OR'APPLICATIONS 6,922 3/1902 Germany 240/64 110,405 5/1900 Germany 240/64 OTHER PUBLICATIONS Osram Lighting Publication, Sept. 1968, pp. l-3.

Primary ExaminerSamuel S. Matthews Assistant Examiner-E. M. OConnor Attorney, Agent, or FirmWallenstein, Spangenberg,

Hattis & Strampel [57] ABSTRACT A light carrying frame preferably in the form of a ringlike structure in spaced encircling relationship to a mast is provided with supporting cables extending upwardly from the frame and around pulleys at the top of the mast. The cables pass down through the mast to a Windlass apparatus at the bottom thereof for raising and lowering the portion of the cables extending upwardly from the frame. Releasable supporting means are provided adjacent the upper portion of the mast for supporting the weight of the light carrying unit when it is raised to a lighting position. Signalling means are provided for signalling to the operator below when the light carrying unit is in its lighting position at the upper portion of the mast.

7 Claims, 11 Drawing Figures FATENTEDAPR 2mm 3.801.813

SHEET 1 UP 3 COMBINATION MAST AND LIGHT RAISING AND LOWERING APPARATUS The present invention relates to a type of recently developed street lighting apparatus which includes a light supporting unit supported on a mast by cables or the like for movement between an upper lighting position adjacent the top of a mast and a lower servicing position adjacent the bottom of the mast where the lighting units can be easily serviced.

In one form of this apparatus, the street light carrying unit comprises a frame in the form of a ring-like structure encircling the mast in spaced relationship and carrying thereon a number of reflector and light assemblies for lighting areas on the street or ground on different sides of the mast. In such case, cables are attached to the ring-like structure at spaced points around the mast and extend upwardly around pulleys mounted adjacent to the top of the mast and then pass down through the mast to a point near the bottom thereof. Usually, three cables are attached to the ring-like structure of the light carrying unit, and adjacent the bottom of the mast the cables are connected to a common swivel coupling from .which a single cable extends to the drum of a Windlass unit. By rotating the drum of the windlass unit in one direction, the cable unwinds from the drum to lower the end portions of the cables attached directly to the ring-like structure. When the street light carrying unit is lowered to a position adjacent the bottom of the mast, the reflector and light assemblies can be serviced as by cleaning the same, changing bulbs and the like. The power conductor leading to the reflector and light assemblies are generally in a common power cable extending through the mast to a junction box at the bottom of the mast and the power cable in such case is disconnected before lowering the light carrying unit. When the drum is rotated in the opposite direction, the cable winds upon the drum to raise the cables attached directly to the ring-like structure. When the light carrying unit is returned to its desired upper position, the drum is stopped.

The combination mast and light raising and lowering apparatus described above has certain disadvantages and limitations overcome by the present invention. In the first place, the various cables suspending the light carrying unit are continuously under tension and often expand to different degrees with the passage of time. Such unequal expansion of the cables causes the light carrying unit to tilt from a desired horizontal orientation. Moreover, there is a danger that if one or more of the cables should break, the relatively heavy light carrying unit can drop to the ground or street below and cause bodily or property damage. Additionally, the cable system described is subject to twisting and jamming, which can greatly affect the life and operability of the cable system. Various aspects of the present invention overcome one or more of the disadvantages described above and provide at the same or at modest increased cost a far superior combination mast and light raising and lowering system.

It is one of the features of the present invention to provide means for supporting the frame of the light carrying unit in its raised lighting position so that the weight of the light carrying unit is normally removed from the cables. The frame support means most advantageously comprises horizontally shiftable means on either the frame or the mast, and apertures or the like in the other of same for receiving the horizontally shiftable means. In the most preferred form of the invention, where the frame of the light carrying unit is a ringshaped structure, the horizontally shiftable means most advantageously comprise at least two and preferably three shoulder-forming members supported on the mast and spring urged outwardly normally to be in the path of upward movement of the ring-shaped frame. Apertures are provided at corresponding points on the frame, and the downwardly facing surfaces of the shoulder-forming members are inclined to form camming surfaces so that when the upper edge of the frame strikes the downwardly facing surfaces of the shoulderforming members, the members are retracted against the force of the spring pressure urging the same outwardly, and these members enter the apertures in the frame when the frame is in its lighting position. When the shoulder-forming members enter the apertures, the frame must usually be dropped to a point where the frame becomes fully supported upon the horizontally extending upper surfaces of the shoulder-forming members. (When the shoulder-forming members are carried on the frame, the upper surfaces of the members are inclined to form camming surfaces, and horizontally extending surfaces on the bottom of the members bear on the lower defining walls of apertures on members carried by the mast.)

In accordance with a more specific aspect of the invention, the various shoulder-forming members are interconnected by coupling means so that the retraction of one of the shoulder-forming members will result in the movement of the rest of the same. A single cable coupled to one of the shoulder-forming members extends downwardly through the mast to a point at the bottom thereof where it is accessible to an operator who when pulling the same simultaneously retracts all of the shoulder-forming members to permit the frame and the reflector and light assemblies carried thereby to be lowered from its uppermost position. In accordance with the broader aspects of the invention, any suitable means may be utilized to retract the shoulderforming members, such as by the use of an electrically controlled solenoids.

In accordance with another aspect of the present invention, to enable the operator to determine when the light carrying unit has been raised to its desired elevation on the mast, signalling means are provided for informing the operator of this fact. While the signalling means can take a number of forms in accordance with the broad aspects of the invention, in the most preferred form thereof such signalling means comprises a pivotally mounted arm carrying a reflector or the like at the end thereof. The signalling unit, which can be mounted either on the mast or on the frame of the light carrying unit, is by counterweighting the same or by other means supported in a position where the reflector or other signalling portion thereof is not readily visible. When the light carrying unit has reached this desired elevation on the mast, the signalling unit is pushed into a generally horizontally extending position where the reflector is readily visible from the bottom of the mast.

Other aspects of the invention deal with the design of the cable system which minimizes or eliminates the twisting and jamming problems previously described, and which minimizes the force necessary to operate the windlass. These features and those just described will be more fully understood together with other advantages of the invention, upon making reference to the specification to follow, the claims and the drawings wherein:

FIG. 1 is a perspective broken-away fragmentary view of a combination hollow mast, street light carrying unit and apparatus for raising and lowering the same FIG. 4 is a vertical sectional view taken along section line 44 in FIG. 2;

FIG. 5 is a vertical sectional view taken along section line 55 in FIG. 2 after the light carrying unit has been raised to its normal lighting position on the mast;

FIG. 6 is a view of the windlass unit mounted in the bottom of the hollow mast in FIG. 1 for supporting and moving various cables shown in FIG. 1;

FIG. 7 is a transverse sectional view through the windlass unit shown in FIG. 6, taken along section line 7-7 therein;

FIG. 8 is an enlarged fragmentary sectional view taken along section line 88 in FIG. 3;

FIG. 9 is a fragmentary vertical sectional view adjacent the top of the mast in FIG. 1 when the light carrying unit thereof has been raised to its normal lighting position and showing'in solid lines the normal position of a signalling means which signals the operator that the light carrying unit is in its normal lighting position and showing in dashed lines the position of the signalling means after the light carrying unit has been lowered from its normal lighting position;

FIG. 10 is a view through the bottom of the mast of FIG. 1 provided with a windlass unit in the bottom thereof for moving and supporting a cable system which utilizes counterweights at the ends of the cables; and

FIG. 1 1 is a fragmentary vertical sectional view of the mast and light carrying unit of FIG. 1 with the windlass unit of FIG. 10 and counterweighted cables used to support the light carrying unit.

Refer now more particularly to FIG. 1 wherein there is shown a hollow mast 1 having a flanged base la anchored in any suitable way to a suitable concrete bed or the like and a head portion lb at the top of the mast upon which is an enclosure 2 housing various pulleys and the like to be described. The mast 1 has an interior space 10 extending between the base 1a and a support plate -2 projecting horizontally from the top of the mast.

Supported on the mast 1 is a light carrying unit 3 which, in the case where a number of lights are to be supported on different sides of the mast, preferably includes a ring-shaped frame 4 supporting at different points thereon around the mast reflector and light assemblies 5. The upper end portions 6a6a-6a of three cables 666 are connected to the frame 4 at three equally spaced points and extend upwardly therefrom where they pass over pulleys (to be described) supported on the support plate 2 and then extends down through the space 1c in the mast 1 where they wind around different axially spaced sections of a drum 8a of a windlass unit 8 mounted in the bottom of the mast space 10. The mast 1 has a door 10 opposite-the windlass apparatus 8 therein, so upon opening of the door the shaft of the drum 8 is accessible for either manual rotation by a crank arm connectable thereto or by external motor apparatus which can be connected in any suitable way to the shaft of the drum 8 0. Suitable slip clutch mechanism preferably interconnects the shaft of the drum 8a and the drum so that any substantial opposition to the rotation of the drum 8a will cause slippage of the shaft with respect to the drum. A power cable 12 extends upwardly from a junction box 13 on the ring-shaped frame 4 and has conductors extending to the reflector and light assemblies where it passes over a pulley to be described and then down through the mast 1 to make connection with a junction box 14 mounted preferably adjacent to the door 10. The power cable 12 can be'readily disconnected from the junction box 14 (and is shown so disconnected in FIG. 1) so that the cable 12 can move up and down freely within the mast along with the cables 66--6. The power cable 12 is preferably anchored to one of the cables 6 at a point initially adjacent to the junction box 14 by a suitable bracket 16 or the like.

In FIG. 1, the light carrying unit 3 is shown in the position where it is somewhat below its normal uppermost position immediately contiguous to the support plate 2 at the head portion of the mast. The light carrying unit 3 can be moved between an uppermost position, sometimes referred to as the lighting position thereof and a fully lowered position adjacent to the bottom of the mast where the reflector and light assemblies 5 can be cleaned, repaired or the light units thereof replaced, by rotating the drum 8a of the windlass unit 8 in one direction or the other (unless the light carrying unit 3 is otherwise held against such movement). When the light carrying unit 3 is lowered to the bottom portion of the mast, the flexibility of the cables 66-6 makes it possible for the ring-shaped frame 4 readily to contact the mast l. Rollers 20 projecting inwardly from the inner margins of the ring-shaped frame 4 are provided which make a rolling engagement with the sides of the mast. The rollers 20 are positioned and spaced on the ringshaped frame 4 so that all the rollers will simultaneously engage the outer surface of the mast 1 when the light carrying unit is in its bottommost servicing position, where a fairly rigid lateral support for the light carrying unit is desired.

In a manner to be described, when the light carrying unit is raised to the lighting position thereof, support means on the light carrying unit and mast become interlocked and, when the light carrying unit is dropped slightly, supports the weight of the light carrying unit so tension is removed from the cables. After the light carrying unit 3 has been returned to its fully raised position, the power cable 12 is reconnected to the appropriate terminals of the junction box 14 in the bottom of the mast 1. While the interlocked support means may be released in a number of ways in accordance with the broadest aspects of the invention, for minimum cost and reliability such release is effected by means of a release cable 19 which extends through the space 1c in the mast l to a point at the bottom of the mast where it is accessible when the door 10 is open.

If the operator should fail to stop the rotation of the shaft of the drum 8a when the light carrying unit 3 is returned to its uppermost position, members 22 to be described carried by the light carrying unit frame 4 will strike the support plate 2', whereupon the drive force supplied to the shaft of the drum 8a will be decoupled from the drum 8a due to the aforesaid slip clutch mechanism. It is preferable that the windlass unit not be operated to a point where these members 22 strike the support plate 2', and for this reason as well as to more easily inform the operator when the light carrying unit has reached its desired lighting position at the top of the mast there is provided signalling means generally indicated by reference numeral 21 to be later described which is automatically moved into a readily visible position when the light carrying unit 3 has been raised to an elevation where the interlockable light carrying unit support means are in interlocked relation, which occurs somewhat prior to the point where the members 22 carried by the frame 4 will strike the support plate 2.

As illustrated in FIG. 5, in the exemplary form of the invention, the frame 4 may be connected to the end portions 6a-6a-6a of the cables 66-6 by means including apertured blocks 22 into which pass cylindrical sleeves 23 firmly secured around the cable ends. The sleeves 23 are anchored within the blocks 22 in any suitable way, such as by anchoring bolts 25 or the like. Each of the cable end portions 6a is shown passing through an opening 24a in a cylindrical member 24 welded or otherwise secured to the bottom surface of the support plate 2' at the top of the mast around an opening 2a formed in the support plate 2'. Each cable then passes over a pair of pulleys 26-28 mounted for rotation in any suitable way upon the support plate 2'. After passing around the pulleys 26-28, each cable 6 passes through a central opening 2b in the support plate 2 and along the inner surface 30a of a cylindrical member 30 secured to the bottom of the support plate 2 around the central opening 2b. As best shown in FIG. 6, at the bottom of the mast each of the cables 6 winds around a portion of the windlass drum 8a partitioned off by a pair of axially spaced walls 80-80, and passes into a radial slot 8b formed in the drum 8a.

As shown in FIG. 4, the support plate 2' has mounted thereon a power cable-receiving pulley 32 around which the aforementioned power cable 12 extends. The portion of the power cable connected to the junction box 13 on the light unit carrying frame 4 passes through the opening 2c in the support plate 2 adjacent the perimeter thereof, and after passing around the one side of the pulley 32 extends through the central opening 2b in the support plate 2 and into the cylindrical member 30 where it extends down throughthe mast.

The aforesaid interlocking support meansfor the light carrying unit 3 may take a variety of forms in accordance with the broadest aspect of the invention. However, in the most advantageous form thereof, this interlocking support means comprises the apparatus now to be described and best illustrated in FIGS. 3, 5 and 8. As thereshown, there is secured to three circumferentially spaced points of the perimeter of the support plate 2 releasable shoulder-forming assemblies 35, 35' and 35. The assemblies are similarly constructed and, except when otherwise stated, it will be assumed that each assembly has the same parts now to be described in connection with FIG. 8 which illustrates the assembly 35. Each assembly, 35, 35 and 35' includes a slide-forming housing 37 in which is formed an open ended horizontally extending slideway 39. Supported for sliding movement in each slideway 39 is a shoulder-forming member 41 having a horizontally extending upper surface 42 and a downwardly facing cam-forming bottom surface 44. The bottom of each shoulder-forming member 41 is provided with a guide slot 46 which receives the projecting end of the guide member 48 which guides the shoulder-forming member 41 for a limited horizontal movement between the position shown in FIG. 8 where the front end of the shoulder-forming member 41 projects radially outwardly of the slideway-forming housing 37 where it is in the path of upward movement of one of the aforementioned frame carried members 22 extending upwardly from the ring-shaped frame 4, and a retracted position where the shoulder-forming member 41 is retracted out of the path of movement thereof. Each shoulder-forming member 41 has a reduced horizontally extending operating rod 50 projecting from the rear thereof. A coil spring 52 surrounds the rod 50 and one end of the spring bears against the rear end of the shoulderforming member and the other end thereof bears against a stationary wall 54 forming part of the slideway-forming housing 37. The end of each rod 50 asso ciated only with assembly 35 terminates in a winged end portion 56 to which the aforementioned release cable 19 is directly connected. As shown in FIG. 5, the end of the release cable 19 connected to the winged end portion 56 passes through a member 47 anchored in a horizontally extending aperture 30b formed in the upper end of the cylindrical member 30 anchored to the support plate 2' and extends down along the inner surface of the cylindrical member 30 where it extends down into the bottom of the mast.

Each frame carried member 22 has an aperture 22a positioned so that when the light unit carrying frame 4 is raised to the top of the mast, the apertures 22a of the member 22 will be brought opposite the shoulderforming members 41 to receive the same. The upper edge portions of the members 22 will first engage the inclined downwardly facing surfaces 44 of the shoulder-forming members 41 and push the same into retracted positions where the upper extremities of the aperture-forming members 22 can pass above the shoulder-forming members 41, and when the frame 4 is raised to its uppermost position, the shoulder-forming members 41 snap into the associated apertures 22a. A slight reversal in the direction of movement of the drum 8a of the windlass unit 8 will then bring the upper defining walls of the apertures 22a of the members 22 down upon the horizontal upper surfaces 42 of the shoulder-forming members 41, thereby to remove the weight of the light carrying unit 3 from the cables.

As previously indicated, when it is desired to lower the light carrying unit from its uppermost position thereof shown in FIG. 5, the release cable 19 is pulled which will withdraw the shoulder-forming member 41 of assembly 35 from aperture 22a of a frame carried member 22. This movement of the latter shoulderforming member 41 is transferred to the other shoulder-forming members of the assemblies 35 and 35' by any suitable means, such as by the provision of flexible cables 60-60 (FIG. 3) contained within conduits 62-62 secured between a wall 63 attached to the housing 37 of assembly 35 and brackets 70-70 forming part of the assemblies 35 and 35 Each flexible cable 60 is connected between the rod 50 of the shoulder-forming member 41 of one of the assemblies 35 and the winged end portion 56 of assembly 35 so that the retraction of the shoulder-forming member 41 of the latter assembly will result in the movement of the flexible cables 60-60 in a direction to retract the shoulder-forming members of the assemblies 35'35.

Refer now to FIG. 9 which shows the construction of the exemplary signalling means 21. As thereshown, the signalling means may include a reflector-carrying arm 75 projecting in a direction outwardly of the ringshaped frame 4 and pivotally mounted at 77 upon a channel member 79 or the like adjustably anchored to the ring-shaped frame 4 by a suitably anchoring means 81 passing through an elongated slot 83 formed in the web of the channel member 79. A spring 85 associated with the pivot of the reflector-carrying arm 75 normally biases the reflector-carrying arm 75 into the inclined position shown in dashed lines in FIG. 9, where the arm 75 assumes a substantial angle, such as 45, to the horizontal. At this angle, a circular reflector 89 or the'like carried on the end of the arm 75 is not readily visible from a point at the base of the mast (or if readily visible assumes an elliptical rather than a circular configuration When the light carrying unit 3 is in its desired uppermost position where the aforementioned shoulderforming members 41 enter the apertures of the frame carried aperture-forming members 22, the reflector carrying arm 75 abuts against the support plate 2' and is depressed thereby against the restoring force of the spring 85 into a horizontally extending position shown in solid lines in FIG. 9, where the reflector 89 readily appears in a circular configuration.

In the cable support system shown in the embodiment of the invention illustrated in FIGS. 1-7, the force applied to the Windlass unit 8 to rotate the drum 8a must be sufficient to overcome the weight of the light carrying unit 3. Refer to the embodiment of the invention shown in FIGS. and 11 wherein the cable system is counterweighted so that a modest force is used which can be readily manually or otherwise applied to rotate the drum 8a of a modified Windlass unit 8. In the modified windlass unit 8, the drum 8a thereof is divided into axially spaced sections by radial extensions 80 where the portion of each of the three cables 6 extending downwardly from a pair of the pulleys 26 and 28 at the top of the mast circles the drum 8a two turns, and extends upwardly through the mast and over a pulley 90, terminating in a cable end portion 6b carrying a counterweight 95. The combined weight of the three counterweights 95 associated with the three cables involved is sufficient to approximately balance out the weight of the light carrying unit 3, so that only a very small force is needed to rotate the drum 8a of the Windlass unit 8 for raising and'lowering the light carrying unit.

It should be understood that numerous modifications may be made in the most preferred forms of the invention illustrated and described above without deviating from the broader aspects of the invention.

We claim:

1. In combination with a hollow supporting mast and a light carrying unit on said mast which light carrying unit includes a frame encompassing the hollow mast,

said light carrying unit being supported by vertical cables secured to said frame at spaced points around the mast and passing over pulleys at the upper portion of the mast and then down through the mast to the lower portion thereof, lighting means carried on the frame, and cable moving means operable from the bottom of the mast which means raises and lowers the cables to move said frame and the lighting means supported thereby between an upper lighting position at the upper portion of the mast and a lower servicing position at the lower portion of the mast, the improvement comprising: frame support means for supporting said light carrying unit at said upper lighting position so the weight of the light carrying unit is removed from the cables, said support means comprising at least two horizontally slidable shoulder-forming members on one of said frame and mast and spring urged toward the other of same, and horizontally facing apertures in the latter positioned to be opposite said shoulder-forming members when said frame is in said upper lighting position so the apertures can receive said shoulder-forming members, each of said shoulder-forming members on one of said frame and mast having an inclined surface facing the other of said frame and mast and engageable by the latter and retracted thereby to permit the shoulderforming member involved to enter the associated aperture in the other of said frame and mast when said frame moves upwardly into said upper lighting position, and manually operable release means operable from the bottom of said mast for retracting said horizon tally slidable shoulder-forming members from said apertures against the spring force applied thereto, to permit the frame and the street lighting means carried thereby to be lowered from said upper lighting position to said lower servicing position by said cable moving means.-

2. The combination of claim 1 wherein said manually operable release means are cable means coupled to said horizontal slidable means to retract the same, said cable means extending to the lower portion of the mast where it is accessible to an operator.

3. The combination of claim 1 wherein there is provided signalling means which signals to the operator at the bottom of the mast when said frame has been raised to said upper lighting position.

4. The combination of claim 3 wherein said signalling means is a member which is mounted for movement on one of said frame and upper portion of the mast and has a relatively non-visible position when said frame is below said upper lighting position and is automatically moved into a relatively highly visible position when the frame reaches said upper lighting position.

5. The combination of claim 3 wherein said signalling means is a member mounted for pivotal movement so it normally assumes an inclined position, and said member being pushed into a generally horizontal position when the frame reaches said upper lighting position.

6. The combination of claim 1 wherein said manually operable release means includes a single cable connected to one of said shoulder-forming members and extending down to the lower portion of said mast, and coupling means coupling the movement of the latter shoulder-forming member against the spring force applied thereto to the one or more other shoulderforming members, so that the operation of a single cable retracts all of said shoulder-forming members into a frame releasing position.

cable on the drum means are kept in alignment, said drum means being rotatable in one direction or the other to raise and lower the portion of the cables extending upwardly from said frame, so the frame can be raised and lowered between said lighting and servicing positions respectively adjacent the upper and lower portions of the mast. 

1. In combination with a hollow supporting mast and a light carrying unit on said mast which light carrying unit includes a frame encompassing the hollow mast, said light carrying unit being supported by vertical cables secured to said frame at spaced points around the mast and passing over pulleys at the upper portion of the mast and then down through the mast to the lower portion thereof, lighting means carried on the frame, and cable moving means operable from the bottom of the mast which means raises and lowers the cables to move said frame and the lighting means supported thereby between an upper lighting position at the upper portion of the mast and a lower servicing position at the lower portion of the mast, the improvement comprising: frame support means for supporting said light carrying unit at said upper lighting position so the weight of the light carrying unit is removed from the cables, said support means comprising at least two horizontally slidable shoulderforming members on one of said frame and mast and spring urged toward the other of same, and horizontally facing apertures in the latter positioned to be opposite said shoulder-forming members when said frame is in said upper lighting position so the apertures can receive said shoulder-forming members, each of said shoulder-forming members on one of said frame and mast having an inclined surface facing the other of said frame and mast and engageable by the latter and retracted thereby to permit the shoulder-forming member involved to enter the associated aperture in the other of said frame and mast when said frame moves upwardly into said upper lighting position, and manually operable release means operable from the bottom of said mast for retracting said horizontally slidable shoulder-forming members from said apertures against the spring force applied thereto, to permit the frame and the street lighting means carried thereby to be lowered from said upper lighting position to said lower servicing position by said cable moving means.
 2. The combination of claim 1 wherein said manually operable release means are cable means coupled to said horizontal slidable means to retract the same, said cable means extending to the lower portion of the mast where it is accessible to an operator.
 3. The combination of claim 1 wherein there is provided signalling means which signals to the operator at the bottom of the mast when said frame has been raised to said upper lighting position.
 4. The combination of claim 3 wherein said signalling means is a member which is mounted for movement on one of said frame and upper portion of the mast and has a relatively non-visible position when said frame is below said upper lighting position and is automatically moved into a relatively highly visible position when the frame reaches said upper lighting position.
 5. The combination of claim 3 wherein said signalling means is a member mounted for pivotal movement so it normally assumes an inclined position, and said member being pushed into a generally horizontal position when the frame reaches said upper lighting position.
 6. The combination of claim 1 wherein said manually operable release means includes a single cable connected to one of said shoulder-forming members and extending down to the lower portion of said mast, and coupling means coupling the movement of the latter shoulder-forming member against the spring force applied thereto to the one or more other shoulder-forming members, so that the operation of a single cable retracts all of said shoulder-forming members into a frame releasing position.
 7. The combination of claim 1 wherein said cable moving means comprises windlass apparatus including drum means carrying separate cable guiding and supporting means around which said cables extending down from the upper portion of the mast are respectively wound and are kept separated, each of said separate cable guiding and supporting means being a groove on the drum means of a width about equal to the width of the associated cable so the various turns of each cable on the drum means are kept in alignment, said drum means being rotatable in one direction or the other to raise and lower the portion of the cables extending upwardly from said frame, so the frame can be raised and lowered between said lighting and servicing positions respectively adjacent the upper and lower portions of the mast. 